Work

Characterizing the influence of Q-stress on mixed-mode I/II fracture in elastic–plastic materials

Year: 2025

Type: article

Abstract: A two-parameter fracture framework is used to investigate the fracture behavior of AM60 magnesium alloy under different loading conditions. Fracture tests were conducted using a modified Arcan apparatus, capable of applying pure tension, pure shear, and mixed tension-shear loading conditions.Various crack-tip constraints were obtained by altering the loading angle from mode-I to mode-II and the crack length ratio between 0.3 and 0.7. The experimental results indicate that the material is more susceptible to crack propagation in tension mode than in shear mode. J C in pure shear demonstrates a decrease of 40.8% relative to J C in pure tension at 0.5 crack length ratio. Finite element analysis was employed to determine the crack-tip constraint parameter (Q) under various loading and geometric conditions, revealing a pronounced dependence of crack-tip constraint on them, with the latter’s effect increasing at higher loading angles. These dependencies were approximated as linear relationships. J-Q curves were developed for different constraint levels to reduce the need for extensive experimental testing. These curves facilitate the estimation of critical J C values directly from the crack-tip constraint.The proposed methodology demonstrated deviations between predicted and experimental J C values ranging from 0.15% to 14.43%. Additionally, the J-R resistance curve was refined to incorporate Q-dependency, further minimizing experimental efforts. The findings underscore the robustness and practicality of this approach in accurately predicting fracture parameters while significantly minimizing extensive experimental requirements fracture tests.

Source: Discover Mechanical Engineering

DOI: 10.1007/s44245-025-00108-4

Authors: Abuzar Es’haghi Oskui, Ata Khabaz-Aghdam, Jinrui Cao, Hosein Hasannezhad, Sajjad Astaraki